Some people fear that ________ air pollution may bring about changes in ________ weather around the world．

/; the

the; /

an; the

the; a

Two hydrogen atoms and one oxygen atom form a polar molecule, ________ with a slightly positive end and a slightly negative end．

which

that

it

one

Once you are in the habit of rushing life, being on the go from morning till night, it is hard ________．

to slow down

slows down

to be slowed down

slowed down

Normally, when eating in a private home, it is considered good manners to take ________ is served and not to ask for something different, ________ the hostess gives you a choice．

whatever; if

whatever; unless

anything; if

anything; unless

________ just south of Yunnan and Guangxi, Vietnam is ________ easy reach and offers exciting adventures at a reasonable price．

Locating; within

Located; in

Located; within

Locating; in

Was it in 2000 ________ he was still in middle school ________ this boy became an expert at computer?

when; that

that; where

when; where

that; that

Can you think of some cases ________ drivers obviously knew the traffic rules but didn't obey them?

why

where

as

which

The two old sisters, who ________ for more than 30 years by the Taiwan Strait, held each other and burst into tears．

have been separated

have separated

has separated

has been separated

There was so much noise in the hall and the speaker could hardly make himself ________．Besides, he could hardly make us ________ him with his poor English．

heard, understood

heard, understand

hear, understand

hear, understood

She ________ be at the airport, for I saw her in the lecture hall five minutes ago．

must not

won't

can't

may